Multi-stage compressor in a plasma cutter

ABSTRACT

Systems and methods are provided for a torch power system using a multi-stage compressor. In one embodiment, a system includes a torch power unit that includes a compressor having multiple compression stages. A method of operation is provided that includes compressing a gas via a multi-stage compressor in a torch power unit. A method of manufacturing a torch power unit is provided that includes providing a multi-stage compressor for a torch power unit and mounting the multi-stage compressor inside an enclosure of the torch power unit. Another system is provided that includes a plasma cutting circuit, a multi-stage compressor, a motor coupled to the compressor, and a compressor controller.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Continuation Application of U.S. patent application Ser. No.12/117,688, entitled “Multi-Stage Compressor in a Plasma Cutter”, filedMay 8, 2008, which is a Non provisional Patent Application of U.S.Provisional Application No. 61/015,175, entitled “Multi-Stage Compressorin a Plasma Cutter,” filed Dec. 19, 2007, both of which are hereinincorporated by reference.

BACKGROUND

The invention relates generally to gas compressors, and moreparticularly to portable torch power systems utilizing an air compressorin a single unit.

A variety of systems use compressed gas (e.g., compressed air). Forexample, compressed air may be used to power tools, such as wrenches,sanders, spray guns, and so forth. By further example, compressed gas(e.g. air) may be used with various torches, such as a plasma cuttingtorch. A plasma cutting system creates plasma (e.g., high temperatureionized gas) to cut metal or other electrically conductive material. Ingeneral, an electrical arc converts a gas (e.g., compressed air) intoplasma, which is sufficiently hot to melt the work piece while thepressure of the gas blows away the molten metal. The power output andflow of the gas can affect the performance of the system.

The compressors in these systems must output a sufficiently high flowrate and pressure of compressed air to power the torch and remove themolten metal or other material being cut. Any reduction in pressure andflow of the air may cause the torch to overheat, cut slower or cut atunacceptable rates, and blow away the molten metal or other materialless effectively. Additionally, the efficiency of the compressor canaffect the power used by the system and the heat generated by thesystem, thus impacting operating costs and cooling requirements.Further, excessive heat, vibration, and/or movement of the compressormay damage or prematurely wear adjacent components and/or the compressoritself.

BRIEF DESCRIPTION

In one embodiment, a system is provided that includes a torch powerunit. The torch power unit includes a compressor having multiplecompression stages.

In another embodiment, a method of operation is provided that includescompressing a gas via a multiple stage compressor in a torch power unit.

In another embodiment, a method of manufacturing is provided thatincludes providing a multi-stage compressor for a torch power unit, andmounting the multi-stage compressor inside an enclosure of the torchpower unit.

In another embodiment, a system is provided that includes a torch powerunit. The torch power unit includes a plasma cutting circuit, amulti-stage compressor, a motor coupled to the compressor, and acompressor controller.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a partial perspective view of an exemplary plasma cuttingsystem having a multi-stage (e.g., two-stage) compressor wherein anentire side panel assembly is removed to further illustrate variousinternal features in accordance with embodiments of the presentinvention;

FIG. 2 is side view of the plasma cutting system as illustrated in FIG.1 wherein compressor housings have been removed to further illustrateinternal features of the multi-stage compressor in accordance withembodiments of the present invention;

FIG. 3 is a block diagram of a plasma cutting system having amulti-stage compressor in accordance with an embodiment of the presentinvention; and

FIG. 4 is a block diagram of a plasma cutting system having amulti-stage compressor in accordance with another embodiment of thepresent invention.

DETAILED DESCRIPTION

Referring now to the drawings, FIGS. 1 and 2 are partial perspectiveviews illustrating an embodiment of a portable plasma cutting system 10having a multi-stage (e.g., two-stage) compressor. Specifically, FIG. 1illustrates the system 10 with an entire side panel assembly removed toprovide a better view of the multi-stage compressor, whereas FIG. 2illustrates a side view of the system 10 with compressor housingsremoved to better view components of the compressor. As discussed infurther detail below, embodiments of the system 10 may include anywelding type apparatus such as a plasma cutting system, welding system,induction heating system etc. that include a multi-stage compressor,such as a two-stage compressor, to provide compressed air to torches,other tools, or other components connected to or disposed in the system10. A multi-stage compressor, such as a two-stage compressor, compressesa gas in two or more compressor chambers connected in series such that afirst compression cycle, a second compression cycle, etc. are executedconsecutively. A multi-stage compressor may have a greater efficiencyand thus use less power and produce less heat than a conventionalsingle-stage compressor, without sacrificing compressor life and/ordurability. Further, multiple stage compressor may be quieter andoperate with less vibration and movement then a conventionalsingle-stage compressor.

The illustrated plasma cutting system 10 includes a torch power unit 12coupled to a plasma torch 14 and a work piece clamp 16 via a torch cable15 and a work piece cable 17, respectively. The torch power unit 12 maybe coupled to a power source (e.g., a power grid or a motor-drivengenerator) via a power cable (not shown). The power source may provide apilot current to a cathode, such as a movable electrode, and to theanode, such as the nozzle of the torch 14, that are forced into contactvia a spring. After electrical current begins to flow from the electrodeto the nozzle of the torch 14, gas or air supplied to the torch 14counteracts the spring force and moves the electrode away from thenozzle. This breaks the electrical contact between the electrode and thenozzle and creates the pilot arc. Also, as the electrode moves away fromthe nozzle, it opens a nozzle orifice (connected to the air supply), anda plasma jet is created. The plasma jet causes the arc to transfer (atleast in part) to the work piece held by the clamp 16, thus initiatingcutting. Electronics in the power source sense when the arc hastransferred and then supply a main cutting current of greater amperageafter the transfer has occurred. Also, the tip of the torch 14 isdisconnected (electrically), interrupting the pilot current path. Thus,the current is used to cut the workpiece, and follows a path includingthe positive terminal, the workpiece and the electrode. For example, thepower unit 12 may be configured to supply a suitable voltage and currentto create an electrical circuit from the unit 12, along the cable 15 tothe torch 14, across a gap between the torch 14 and a work piece (e.g.,as an electrical arc), through the work piece to the clamp 16, andthrough the cable 17 back to the unit 12. In alternate embodiments, anon-moving electrode torch may be used in which a pilot arc is createdvia a high voltage and/or high frequency circuit, so that the highvoltage may cause the arc to jump from the non-moving electrode to thenozzle. In yet other embodiments, any suitable torch and startingtechnique may be used.

The power unit 12 includes an enclosure 20 defining a generally closedvolume to support various circuits, sensor features, control features,and gas supply features (e.g., air compressor). As discussed in detailbelow, the illustrated system 10 includes a variety of features toimprove portability, serviceability, reliability, and control of theplasma torch 14 and the components within the single enclosure 20 of thesystem 10. As shown in FIGS. 1-2, the top portion and side portions ofthe enclosure 20 have been removed to better illustrate the interiorcomponents. The illustrated system 10 also may include a handle on thetop side of the enclosure 20 to enable easier transportation of thesystem 10. The enclosure 20 may also include vents 28 to relieve heatand/or pressure inside the system 10. Additional vents may be located onother panels of the enclosure 20.

In accordance with an embodiment of the present invention, the system 10may include a two-stage compressor 30. The compressor 30 may be poweredby a compressor motor 32, such as a DC or AC motor that may includebrushed, brushless, switched, reluctance, or any other suitable type ofmotor. In certain embodiments, the system 10 may include a flow meter,pressure sensor or other sensor configured to monitor output of thecompressor 30. The system 10 also may include sensors, such as apressure sensor, a temperature sensor, or a combination thereof, toprovide feedback used to adjust the motor 32, the compressor 30, powerelectronics 34, or a combination thereof. The power electronics 34 maybe configured to condition and provide power to the torch 14 and thecompressor 30, and may include transformers, circuit boards, inductors,terminals, capacitors, other electrical components, and/or othercomponents. Multiple fans 36 may also be included inside the system 10to provide air circulation and cooling to the system 10. Additionally,as depicted in FIG. 2, the fans 36 may be located next to one of thevents 28 to optimize air circulation. Additional fans 36 may be includedat other locations inside or outside the enclosure 20. For additionalcooling of the compressor 30, a heat sink 37 may be coupled to the topof the compressor 30. The system 10 may also include an airflow director37 that may form a windtunnel to direct cooling air over the coolingcomponents of the system 10 and to contain dirt and debris drawn in bythe cooling fans 36.

In the illustrated system 10, a control panel 38 is included at an endof the power unit 12. The control panel 38 may include various controlinputs, indicators, displays, electrical outputs, air outputs, and soforth. In an embodiment, a user input 40 may include a button, knob, orswitch configured to enable selection of a mode of operation (e.g.,plasma cut, weld, etc.), power on/off, an output current level, a gas(e.g., air) flow rate, a gas (e.g., air) pressure, a work piece type, acontrol type (e.g., manual or automatic feedback control), or acombination thereof. The control panel 34 may also include variousindicators 42 to provide feedback to the user. For example, theindicators 42 may include one or more light emitting diodes (LED) and/orliquid crystal displays (LCD) to display on/off status, current level,voltage level, gas (e.g., air) pressure, gas (e.g., air) flow,environmental conditions (e.g., altitude, temperature, pressure, etc.),or any other parameter. Additionally, the indicators 42 may include anLED or LCD that displays a trouble or warning indicator if there is aproblem with the system 10. Embodiments of the control panel 38 mayinclude any number inputs and outputs, such as welding methods, aircompressor settings, oil pressure, oil temperature, and system power.For example, the indicators 42 may display an indication of the stage(e.g., one, two, three, etc.) of the compressor 30.

The plasma torch 14 includes a handle 44, a locking trigger 46, a tip48, a retaining cap 52, as well as an electrode inside the torch 14. Theclamp 16 comprises an electrically conductive material clamping portion54 having insulated handles 58. The system 10 may be configured to workwith a variety of sockets or outlets, and the system 10 may receivedifferent power sources, such as AC 50/60 Hz, 400 Hz, single or threephase 120V, 230V, 400V, 460V, 575V, etc. Additionally, the system 10 mayinclude additional components and is not limited to the componentsillustrated in FIGS. 1-2.

In some embodiments, as mentioned above, the system 10 may providecompressed air to other tools or components coupled to the system 10.For example, in such an embodiment, the compressor 30 may provide air togrinders, impact wrenches, nail guns, drills, or any other suitabletool. The system 10 may include a 3-way or 4-way solenoid valvedownstream of the compressor 30, such that the compressed air outputfrom the compressor 30 may be directed to the torch 14, another tool, ora combination thereof. In one embodiment having a solenoid valve, one ofthe user inputs 40 on the control panel 38, e.g., a user interfaceselector switch, may allow a user to direct the compressor output to thetorch 14 or to another tool. Additionally, use of a 4-way valve providesa fourth path for the compressed air output of the compressor. The 4-wayvalve may divert air to the torch 14, may divert air to another attachedtool, and/or may act as an exhaust valve to rapidly decompress air tothe torch 14 or tool. In some embodiments, it may be desirable to purgeand decompress the pressurized gas feeding the torch or tool as quicklyas possible to ensure rapid re-fire of the plasma torch or restart ofthe tool.

Alternatively, in some embodiments the 3-way or 4-way valve may beconfigured to sense the attachment of another tool, such as through asensor that detects a flow or pressure resistance caused by the attachedtool. In such an embodiment, the 3-way or 4-way solenoid valve mayautomatically divert air to the attached tool instead of the torch 14.

Turning now in more detail to FIG. 2, the system 10 includes the fan 36,the gas compressor 30, cooling coils 60 and 61, and pneumatic couplings62. The compressor 30 may include or may be connected to the DC motor 32that is connected to power electronics 34 inside the system 10 and thatdrives the compressor 30. The gas compressor 30 may be rigidly mountedinside the enclosure 20 using compressor mounts such as rubber mounts,plastic mounts, metal mounts, or any other material. The compressormounts may be configured to dampen vibrations of the compressor or toallow slight movement of the compressor 30 during operation.

In the illustrated embodiment, the gas compressor 30 intakes andcompresses air directly from the atmosphere, such as via a filter, andmay use one of the vents 28 as an intake vent to enable air to flow intothe compressor 30. The gas used by the compressor 30 may be a gas, suchas nitrogen, argon, hydrogen, oxygen, or any combination thereof.Accordingly, the gas compressor 30 may provide a direct supply ofcompressed gas (e.g., air) on-demand to a desired application, such asthe plasma torch 14. Thus, the torch 14 may consume air directly fromthe unit 12 without the air being compressed into a tank.

To ensure reliability and performance for the system 10, varioustemperature sensors (e.g., thermistors) may be included inside theenclosure 20 to measure the temperature of various components. Forexample, the system 10 may include a temperature sensor configured tomeasure the temperature of the motor 32, the compressor 30, the powerelectronics 34, atmospheric air, and so forth. In addition to eachtemperature sensor, the system 10 may include control and/or monitoringlogic to receive signals from the temperature sensors and perform theappropriate action or indication. For example, if the signal from one ormore of the temperature sensors (e.g., thermistors) exceeds a thresholdtemperature or voltage for a component, then the control and monitoringlogic may provide a visual warning by activating a LED or LCD 42 on thecontrol panel 38. If the signal from a temperature sensor (e.g.,thermistor) exceeds another threshold temperature or voltage and/or thesignal remains above the threshold for a specific duration, then thecontrol and monitoring logic may shutdown the system 10 or thatcomponent. The control and monitoring logic may prevent use of thesystem 10 until the signals from the temperature sensors fall below thethreshold levels.

For example, the system 10 may include control circuitry in the vicinityof the control panel 34. In one embodiment, the control circuitry mayinclude a processor, memory, and software code configured to control andor coordinate operation of the system 10.

The system 10 may include cooling components such as the heat sinks 37and may include active cooling via the fan 36. The heat sink 37 may bemounted such that airflow from the fan 36 circulates air around the heatsink 37, further enhancing the cooling capability of the heat sink 37.As discussed above, additional fans may be included in other locationsin the system 10. Similarly, additional heat sinks may be placed insidethe system 10 depending on those areas that need passive cooling and/orcannot be cooled by any of the fans in the system 10. Thus, in otherembodiments, the system 10 may include any number and combination ofactive and passive cooling components.

During operation of the system 10, a user first connects the system to apower source, such as a wall socket, via the power cable (not shown). Auser may then turn on the system 10 via the user input 40. Thecompressor 30, fan 36, and other components of the system 12 receivepower from the power electronics 34 and begin operation after the userinput is activated and the control circuitry calls for operation. A userthen attaches the clamp 16 to a work piece (e.g., metal or othermaterial) to be cut. To begin cutting the work piece, the user placesthe cutting torch 14 adjacent the work piece and activates the trigger46, which may involve raising a locking mechanism to free the trigger 46before depressing the trigger 46. Compressed gas from the gas compressor30 passes through the cooling coils 60 and 61, through the torch cable15, and out the tip 48 of the torch 14. As discussed above, a pilotcurrent may be supplied between a moveable electrode and the nozzle ofthe torch 14, thus establishing a pilot arc when the moveable electrodeis pushed away from the nozzle of the torch 14 by the gas supplied bythe compressor 32. As the electrode moves away from the nozzle of thetorch, gas flowing through the torch 14 is energized into a plasma jetwhich in turn transfers the arc to the work piece.

The electrical arc heats up the gas from the compressor 30, convertingit to plasma that is hot enough to cut the work piece. As the user movesthe torch 14 across the work piece by dragging, using a drag shield,standoff guide, or the like, the material is cut as the plasma movesthrough the material. The thickness of the material being cut may belimited by the power of the system 10, the output of the compressor 30,and the torch 14. In addition to supplying the plasma, the compressedgas from the compressor 30 cools the torch 14 and blows away moltenmaterial (e.g., molten metal). At the end of the cut, the user releasesthe trigger 46 of the torch 14. Gas may continue to flow through thetorch 14 for a period of time sufficient to cool the consumables, in astate known as “postflow.” The postflow cools the torch 14 and ensuresthat any remaining material is blown away. After postflow, a user mayshutdown the system 10 via one or more user inputs 40 on the controlpanel 38.

Referring now in more detail to the multi-stage compressor 30 asdepicted in FIG. 2, operation of the multi-stage compressor 30 includesair flow through a series of pipes and cooling coils 60 and 61 beforeexiting through the torch 14. For example, in one embodiment, thecompressor 30 has two compression chambers 70 and 72 in series.Initially, the compressor intakes air into the first compression chamber70. After the first stage of compression, compressed air then passesthrough a first tube 74 to a cooling coil 60. After passing through acooling coil 60, the air enters the second chamber 72 for the secondstage of compression. After a second stage of compression in the secondchamber 72, the air enters a second cooling coil 61 for further cooling.The cooling coils 60 and 61 provide removal of heat after the first andsecond compression stages have compressed the gas. After exiting thecooling coil 61, the compressed gas is then passed through the torchcable 15 to the torch 14. In alternate embodiments, as discussed furtherbelow, the compression chambers 70 and 72 may operate in parallel.

In one embodiment, the first chamber 70 and the second chambercompression cycles may run in-phase, such that the both the firstchamber 70 and second chamber 72 are intaking and expanding at the sametime. In other embodiments, the first chamber 70 may run slightly orsubstantially out-of-phase with the second chamber 72. For example, insome embodiments the first chamber may run 5, 10, 15, 20, 25 or 30degrees out of phase with the second chamber 72.

In one embodiment, the multi-stage (e.g., two-stage) compressor mayoutput at least about 70 psi at about 6.5 standard cubic feet per minute(scfm). In such an embodiment, the first stage of the multi-stagecompressor 30 may compress a gas from atmospheric pressure (about 14psi) to about 45 psi, and the second stage may compress the gas fromabout 45 psi to about 70 psi. In one embodiment, the two-stagecompressor 30 may be a WOB-L® piston compressor manufactured by ThomasProducts Division of Sheboygan, Wisconsin. In such an embodiment, eachcompression chamber 70 and 72 may use a connection rod fixed at the headof the piston and the crankshaft such that the piston rotates in thechamber as it moves up and down. In such an embodiment, the service lifeand output of the two-stage compressor may be affected by the cup seal(seal between the piston and chamber walls), and the cup seal may beselected to obtain a desired service life for the compressor 30.

FIG. 3 is a block diagram of the two-stage compressor system within theplasma cutting system 10 in accordance with an embodiment of the presentinvention. The illustrated embodiment includes the power electronics 34,a power generator 82, the motor 32, the compressor 30 having first andsecond stages 83 and 84, an interface 86, and a compressor controller88.

The illustrated system 10 may be connected to a power source 90, such asa power grid or a power generator. The compressor 30 is driven by themotor 32, which may be controlled by the compressor controller 88. Asdiscussed above, the motor 32 may be an electric motor, such as a DC orAC motor that may include brushed, brushless, switched, reluctance, orany other suitable type of motor, or a gas combustion engine. Forexample, the motor 32 may include a two-stroke or four-strokespark-ignition engine, which includes one or more reciprocating pistonin cylinder assemblies, a carburetor or fuel injection system, and soforth. Some embodiments of the system 10 may include the power generator82 built-in or integrally disposed within the enclosure 20 of the powerunit 12. Thus, the motor 32 may drive both the compressor 30 and theelectrical generator 82, thereby making the power unit 12 completelyportable for use in remote locations. However, other embodiments mayexclude the generator 82 to reduce the size, weight, and cost of thepower unit 12. Additionally, power electronics 34 provide the powermanagement functions for the system 10. In some embodiments, the powerelectronics 34 include a plasma cutting circuit, a welding circuit, apower conditioning circuit, a user input/interface circuit, a powergenerator circuit (e.g., if the unit 12 includes the generator 82), amulti-stage compressor control circuit, or any combination thereof.

As discussed above, the compressor 30 may be a multi-stage compressor,such as a two-stage compressor as shown in FIG. 3. An air intake 92 mayallow the compressor to intake air from outside the enclosure 20 of thesystem 10. The air passes sequentially through the first stage 83 andthen the second stage 84 before passing to the torch 14. However, thecompressor 30 may have any number of compression stages, such as 1, 2,3, 4, 5, 6, 7, 8, 9, 10, or more. However, in one embodiment, themultiple stages (e.g., stages 83 and 84) may always work together toprovide the output pressure/flow to the torch 14. In either case, themulti-stage design of the compressor 30 may substantially reduced noise,heat generation, and power consumption (e.g., 25 to 35% less powerconsumption). Again, as described above, cooling coils, filters, orother components may be used downstream of the compressor 30 to cool orcondition the compressed air before it passes to the torch 14.

FIG. 4 is a block diagram of the two-stage compressor system within theplasma cutting system 10 in accordance with another embodiment of thepresent invention. For convenience, the same components and numbering ofFIG. 3 are illustrated in FIG. 4. However, in contrast to FIG. 3, thecompression stages 83 and 84 of the compressor 30 operate in parallel.For example, initially, the compressor 30 intakes air into bothcompression stages 83 and 84. The air intake 92 may allow the compressorto intake air from outside the enclosure 20 of the system 10 into thefirst stage 83 and the second stage 84 in parallel. Compressed air fromthe first stage 83 joins with the compressed air output of the secondchamber 84 before passing to the torch 14. As in other embodiments, thecompressor 30 may have any number of compression stages, such as 1, 2,3, 4, 5, 6, 7, 8, 9, 10, or more. However, in such an embodiment, themultiple stages (e.g., stages 83 and 84) may always work together toprovide the output pressure/flow to the torch 14.

It should be appreciated that the multi-stage compressor 30 and torchpower unit 12 is applicable to other tools using a gas compressor. Forexample, an engine-driven welding system that includes an engine,generator, may also use a multi-stage compressor such as the two-stagecompressor described herein. Further, an induction heating system, awelding system, a plasma cutting system, or any system that includes orprovides compressed air may also implement the multi-stage compressorsystem described herein.

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

1. A system, comprising: a torch power unit, comprising: power electronics configured to provide power to a torch; a compressor having multiple compression stages configured to compress a gas to provide a compressed gas output to at least one device coupled to the compressor; and a first cooling coil coupled to the compressor and configured to cool the gas downstream of a first stage of the multiple compression stages and upstream of the at least one device.
 2. The system of claim 1, wherein the compressor comprises a plurality of compression chambers configured to compress the gas in the multiple compression stages, wherein each of the plurality of compression chambers operates in series with the others of the plurality of compression chambers.
 3. The system of claim 1, wherein the compressor comprises a reciprocating compressor having at least two compression stages.
 4. The system of claim 1, wherein the torch power unit comprises a control panel configured to switch the compressed gas output of the compressor between the torch and the at least one device based at least in part on an input to the control panel.
 5. The system of claim 1, wherein the power electronics comprise a welding circuit, cutting circuit, induction heating circuit, or combination thereof.
 6. The system of claim 1, wherein the power electronics comprise a plasma cutting circuit, and the compressor is configured to provide the compressed gas output to the torch to generate a plasma to cut a work piece.
 7. The system of claim 1, wherein the torch power unit comprises an electrical generator.
 8. The system of claim 1, comprising a second cooling coil coupled to a downstream end of the compressor, wherein the first cooling coil is coupled between the first stage of the compressor and a second stage of the compressor.
 9. The system of claim 1, wherein the at least one device comprises a pneumatic tool.
 10. The system of claim 1, wherein the compressor comprises at least three compression stages.
 11. The system of claim 1, comprising a fan configured to circulate air about the torch power unit.
 12. A method of operation, comprising: compressing a gas via a multi-stage compressor in a torch power unit to provide a compressed gas, wherein compressing the gas comprises compressing the gas in a first chamber and a second chamber of the multi-stage compressor; cooling the gas via at least one cooling coil after compression in the first chamber; outputting the compressed and cooled gas from the torch power unit for supply to a plasma cutting torch; and outputting a power from the torch power unit for supply to the plasma cutting torch.
 13. The method of claim 12, comprising cooling the gas after compression in the second chamber of the multi-stage compressor.
 14. The method of claim 12, comprising controlling the compressed gas and the power output by the torch power unit to control a plasma generated at the plasma cutting torch.
 15. The method of claim 12, comprising generating an arc between the plasma cutting torch and a workpiece using the power, generating the plasma with the arc and the gas at the plasma cutting torch, and cutting the workpiece with the plasma.
 16. The method of claim 12, comprising driving the multi-stage compressor via a gas combustion engine.
 17. A method of manufacturing a torch power unit, comprising: providing a multi-stage compressor for a torch power unit; coupling at least one cooling coil to the multi-stage compressor, wherein the multi-stage compressor is configured to compress gas via a plurality of compression chambers, and the at least one cooling coil is configured to cool the gas downstream of at least one compression chamber of the plurality of compression chambers; and mounting the multi-stage compressor and the at least one cooling coil inside an enclosure of the torch power unit.
 18. The method of claim 17, wherein the at least one cooling coil is configured to cool the gas downstream of the plurality of compression chambers of the multi-stage compressor.
 19. The method of claim 17, comprising mounting a welding circuit, a cutting circuit, or both, inside the enclosure.
 20. The method of claim 17, comprising mounting at least one of a fan and a heat sink at least partially inside the enclosure. 